Electrical device



May 14, 1935. A. NYMAN 2,001,282

ELECTRICAL DEVICE Original Filed Oct. 1, 1925 INVENTOR m ALEXANDER Wynn/v I00 1 I 7 W M ATTORNEYS Patented May 14, 1935 UNITED STATES PATENT OFFICE ELECTRICAL Alexander Nyman, Dobbs Ferry, N. Y., assignor to Dubilier Condenser Corporation, New York, N. Y., a corporation of Delaware Application October 1, 1925, Serial No. 59,876 Renewed April 20, 1932 9 Claims. (01. 175-415) This invention relates to electrical devices, also shown as approximately spiral, and when especially electrical condensers for radio and the straight edges of the plates l and 2 coincide, other electrical apparatus. as indicated in Figure 1, the capacity of the con- An object of this invention is to provide a denser is of course at its maximum because the condenser adapted for electrical oscillations of maximum areas of the fixed and movable plates 5 relatively high frequency; the condenser comare then in overlying position. As the shaft 3 prising fixed and movable parts, the latter of is turned anti-clockwise for example, the capacsuch design that the condenser can be suitably ity is decreased. I prefer to make the plate or connected and adjusted to give a variation of plates 2 such that the curved edge 4 has the form wave length or frequency approximately in proof a linear spiral, which can be expressed by the 10 portion to the amount of displacement of such equation r=a+b:c; r being the radius of curvamovable parts. ture, a and b, constants, and a: the angle through Further objects and advantages of this invenwhich 1' revolves, the center of revolution being tion will appear from the following description the axis of the shaft 3.

l5 taken with the drawing; and the novel features The shape of the plates l and 2 is thus chosen 16 are pointed out in the appended claims. But the that the capacity of the condenser when propdisclosure is of course illustrative "only, and I erly connected can be varied to give a change of may vary the details of the several embodiments wave length that is substantially in direct proof my invention actually shown herein without portion to the angle of movement through which 20 departing from the principle of the invention, or the shaft 3 carrying one or more plates 2 is ro- 20 exceeding the scope or meaning of the terms in tated. For example, to adjust for a wave length which the claims are expressed. 1 halfway between minimum and maximum, the

On the drawing:- shaft is moved through only 90 degrees from the Figure 1 is a more or less diagrammatic view, position of minimum capacity, instead of 180 dein front elevation of avariable condenser used grees therefrom to the position shown in Fig- 25 in the practice of my invention; ure 1.

Figure 2 is a view of another form of such a In Figure 3, the diagram of connections for (ionlllensel';v the circuit is presented. The variable condenser Figures 3 and 4 illustrate circuits including is indicated at C, and it is in multiple with an such condensers, connected to give the result inductance coil 5. At 6 and Tare shown the con- 30 d ductors or main leads of the circuit, and these Figure 5 is a side view, and leads are joined to the terminals of the condenser Figure 6 an end of a variable condenser used in and of the inductance by the branch conductors the practice of my invention, operatively com- 8 and 9. In this arrangement the wave length bined with a small condenser of constant cavaries according to the angle of rotation of the 35 vpacity; and shaft 3, the wave length decreasing as the shaft Figure 7 is a chart to show the results of the 3 turns to decrease capacity by moving plates l mode of operation. and 2 apart; and vice versa.

The same numerals identify the same parts If one wishes to secure, by changing the capac- 40 throughout. ity of the condenser, a variation in the frequency 40 In Figure l the numeral l indicates a fixed or of the oscillations, and 'to make the variation in stationary conductor plate, supported in any confrequency substantially proportional to the anvenient manner, this plate to be connected .to gle of rotation of the member 2, a small fixed conone terminal of the circuit in which the condenser c is connected in parallel with the condenser is to be used. In shape this plate may be denser of either Figure 1 or Figure 2. The cir- 45 spiral or semi-circular, and there may be one or cuit will then be as shown in Figure 4. Here the more than one in any number desired. To co-- frequency increases as the capacity of the conoperate with the plate or plates l, I mount in dense s dec eased, and Vice V aproximity thereto a corresponding number of The method of mounting the fixed condenser plates 2, all affixed to a rotatable shaft'or axis a. in pla on the adjusta l nd s s wn in 50 These plates 2 can therefore be moved with re- Figures 5 an At is indicated the 09151118 spect to the plates l. The fixed plates and the closing the parts of the variable condenser, the movable plates are of course disposed in altershaft l6 of which, carrying the movable members, nation, and the plates 2 are connected to the opbears an operating knob I1. On the front of 'posite terminal of the circuit. The plate 2 is this casing adjacent this knob maybeagraduated 55 scale or dial. The fixed condenser c is affixed to terminals i8, protruding from the back of the casing, these terminals being joined one to the movable member and one to the fixed member or members thereof.

Figure 7 is a chart showing the variations of wave length and frequency in kilocycles proportional to the degree of movement or rotation of the member or members 2, as indicated by the scale, the positions of which are numbered at the bottom of this chart. The two curves W and F are given respectively by the circuits shown in Figure 3 and Figure 4.

Figure 2 illustrates a condenser comprising a fixed semi-cylindrical conductive member or armature I0, corresponding to the plate or member in Figure 1, and cooperating with this member I0 is a rotatable member Ii also semi-cylindrical corresponding to the plate or member 2. The center of curvature of the member I0 is shown at l2, and that of the member H at l3; while at [4 is the axis of rotation about which the member ll turns. When the parts In and H are in position of maximum capacity, the points l2 and I3 will coincide. The member Hi can be supported and the member I i mounted as before in any suitable fashion. It will be seen that as the condenser of Figure 2 is adjusted to full capacity, the distance between the two members decreases, as the overlying areas increase, and the wave length also increases. The condenser of Figure 2 can be connected like the first condenser, as shown at C in both Figure 3 and 35 Figure 4.

Having described my invention, what I believe to be new and desire to secure and protect by Letters Patent of the United States is:

1. The combination of a variable condenser having a fixed member and a movable member adapted to give substantially a straight line wave length relation, and a'condenser of constant and relatively small capacity bridged across the terminals of the variable condenser and cooperating therewith to change the capacity relation of said members to one more closely approximating a straight line frequency relation.

2. A variable condenser comprising a fixed member and a rotatable member in cooperative relation, the said members comprising substantially semi-cylindrical elements having curvatures concentric. to each other in a position of maximum overlap, the said rotatable member having a center of rotation at a point different from its center of curvature, the elements being adapted to give substantially a straight line wave length characteristic relative to angular displacement of the movable member, and a condenser having a capacity of less than twenty per cent of the maximum capacity of said vari able condenser bridged across the terminals of the elements and changing the-said characteristic to approximately straight line frequency relative to angular displacement of the movable member.

3. The combination of a variable condenser having a fixed ember and a rotatable member which give a non-linear relation of capacity to angular displacement of the rotatable member, and a relatively small fixed condenser connected in parallel with said variable condenser, the resultant combination having a capacity variation with angular displacement of the rotatable member which more closely approximates a straight line frequency characteristic.

4. In combination, a variable condenser comprising a fixed member and a rotatable member; said rotatable member being substantially semicircular and having a center of rotation displaced from its center of curvature to a point such that the rate of change of capacity with angular displacement of said rotatable member continually increases according to a substantially straight line wave length characteristic; and a fixed condenser connected in parallel with said variable condenser and having sufilcient capacity to modify the rate of change of said variable condenser to give a substantially straight line frequency characteristic.

5. In combination, a variable condenser having a fixed plate; a rotatable plate having a curved edge which follows the form of a linear spiral, and a fixed condenser connected across said variable condenser and having sufiicient capacity to give to the resultant combination a variation of frequency substantially in proportion to angular displacement of the rotatable plate.

6. In combination, a variable condenser having a fixed plate, a rotatable plate having a curved edge which follows the form expressed by the equation r=a+b:r, and a fixed condenser connected across said variable condenser and having sumcient capacity to give to the resultant combination a variation of frequency substantially in proportion to angular displacement of the rotatable plate.

'7. A condenser system comprising a variable condenser oi the straight line wave length type and a relatively small fixedcapacity condenser connected in parallel therewith and so arranged that the combination will result in substantially a straight line frequency relation in the variable condenser.

8. The combination of a variable condenser having a fixed member and a movable member adapted to give a change of wave length substantially in proportion to displacement of said movable member, and a condenser of constant capacity bridged across the terminals of the variable condenser to cooperate therewith and give a change of frequency substantially in proportion to the displacement of the movable member.

9. The combination of a variable condenser having a fixed member and a movable member adapted to give a substantially straight line wave length characteristic with angular displacement of the movable member, and a relatively small fixed capacity bridged across the terminals of the variable condenser and changing the said characteristic to approximately straight line frequency relative to said displacement.

ALEXANDER NYMAN. 

